Method for qualitatively and quantitatively improving the fertilizing or leaf dressing of cultivated and ornamental plants in greenhouses, outdoors or agriculture

ABSTRACT

A method of qualitatively and quantitatively improving the fertilization of plants comprising impregnating a plant nutrient salt solution, optionally containing herbicides, fungicides or insecticides, with an amount of CO 2  effective to economically increase the solubility of said nutrient salt whereby the quantitative uptake through the surface is improved.

CROSS REFERENCE TO RELATED APPLICATION

This application is related to Ser. No. 642,031 filed Aug. 17, 1984.

FIELD OF THE INVENTION

This invention relates to a method of qualitatively and quantitativelyimproving the fertilizing or leaf dressing of cultivated and ornamentalplants in greenhouses, outdoors or in agriculture, comprising the stepsof preparing an aqueous solution enriched with nutrients, herbicides orpesticides and directly spraying or aerosolizing the same on the leavesof the useful and/or ornamental plants through nozzle systems.

BACKGROUND OF THE INVENTION

In closed greenhouses, the irrigation water is known to be enriched withcarbon dioxide gas to enhance both the growth and resistance of theplants to diseases and pests by influencing the quality of the soil. Oneof the known irrigation systems may be employed for introducing thewater impregnated with carbon dioxide into the soil, such as, forexample, the drip irrigation system, the channel irrigation system, thecatchment type irrigation system and the rain gun type irrigationsystem. For the introduction of the water enriched with CO₂ into thesoil, it is essential that the absorptivity for CO₂ in water should beincreased above the normal absorbing capacity and that a fineimpregnation should be achieved, which prevents free bubbles in theirrigation water from impairing or blocking the supply-, dosing-andnozzle systems or the like.

Owing to the high degree of impregnation, the spraying or aerosolizingof the so high and fine impregnated irrigation water results in lossesin CO₂ already upon the discharge of the irrigation water andconsequently, renders these types of irrigation system less economical.

On the other hand, the spraying of irrigation water has gainedimportance for so-called leaf dressing or fertilizing. In leaf dressing,one utilizes the capability of the plants to directly take up nutrientsthrough the leaves and sprays nutrient solutions, to which fungicides orother pesticides may be also added, directly on the plants leaves. Indoing so, difficulties often arise due to the fact that the fine supplyand nozzle areas of the nozzle system are impaired or clogged bydeposits of the dissolved nutrients, herbicides or pesticides. Hence,these systems require continuous maintenance and cleaning. Anotherdisadvantage is to be seen in the deposits and spots formed on the plantsurface. Moreover, when this system is used, the substances are to beconverted to a compound, for example, a chelate, adapted to be bettertaken up by the plants, a fact that makes the method more expensive andimpedes its large scale employment.

OBJECT OF THE INVENTION

It is an object of the present invention to improve this leaf dressingmethod by increasing the reliability of the nozzle systems and byimproving both quantitatively and qualitatively the nutrient uptakethrough the leaves, with deposits on the plant surface being largelyavoided.

SUMMARY OF THE INVENTION

This object is achieved in that the aqueous solution or the water usedfor producing said solution is impregnated with CO₂ gas up to a contentthat ranges within the natural absorbing capacity of water for CO₂ gasat ambient temperature and at atmospheric pressure or is slightlygreater.

The method makes use of the capability of the plants leaves to directlyabsorb both macro- and micro nutrients and supply the same to themetabolism of the plant. This nutrient uptake through the leaves maysubstantially be enhanced and favored by adding--in accordance with thenew method--to the nutrient solution or to the irrigation water used forthe production of the nutrient solution, carbon dioxide gas inquantities that amount to or slightly exceed the normal absorbingcapacity of the water at ambient temperature. The normal absorbingcapacity for carbon dioxide gas in water having a temperature ofapproximately +20° C. is about 0.88 l gas/l pure water, approximatelycorresponding to 1.78 g of CO₂ per liter water. Since the normal tapwater already contains foreign gases or other foreign matter, inpractice, the normal absorbing capacity is lower than the given value.Increasing the CO₂ content above the normal value will result in asubstantial increase in the solubility of the water for the nutrientsalts. Consequently, when the water is impregnated with CO₂ the nutrientsalts will not so easily crystallize out of the nutrient solution ordeposit in a different manner and therefore, any clogging of theconduits and nozzles of the nozzle or spraying system and of the plantstake-up organs is largely excluded. Hence, the systems need not bemaintained so often and the aftertreatment of the plants is alsosubstantially reduced, with the reliability of the spraying system beingessentially increased at the same time. It is thereby ensured, that thenutrient solutions can be extraordinarily uniformly placed on the leavesof the useful plants.

Hitherto, the applicability of leaf dressing has been limited. Incontrast thereto, acid formation takes place in the direct vicinity ofthe roots when the soil is fertilized--above all, carbonic acid isformed which causes an increased availability.

Such an acid is formed whenever carbon dioxide, respired by the roots,physically penetrates into the nutrient water. Chemically dissolvedcarbonic acid is thereby formed at a ratio of 1:1,000 with regard to thephysically dissolved carbon dioxide. This acid forms hydrogencarbonatesand makes cationic minerals available to the plant.

However, on the leaf surface the plant cannot dispose of such a system.In accordance with the present invention, the water is consequentlyenriched to some extent with CO₂, whereby the quantitative nutrientuptake through the surface is improved. There is also a qualitativeimprovement to the effect that any detrimental, pore-cloggingcrystallization or deposit is largely excluded owing to the increasedsolubility. Due to an increased nutrient salt concentration in thedressing water on the leaf surface--caused by the impregnation with CO₂--a higher osmotic gradient results. Consequently, the plant surface iscapable of taking up more nutrients. This increased take-up capacity isalso maintained in case CO₂ is taken up through the stomata, since theCO₂ concentration increases again simultaneously with the evaporation sothat the solvency is maintained to a large extent until the evaporationprocess has terminated.

Since the CO₂ content is adjusted to some extent, there are only slightlosses in CO₂ when the nutrient solution is sprayed. Consequently, whenthe water spray mist precipitates on the leaves of the plants, theoriginally adjusted CO₂ content is substantially maintained, even in arelatively stable manner, and therefore, the carbon dioxide contained inthe water also substantially improves the nutrient uptake of the plantsthrough the leaves, since in this case as well, the solubility of thenutrient salts in water is greater than in non-impregnated water owingto the carbon dioxide content. Accordingly, upon evaporation of thewater mist falling on the leaves, the carbon dioxide is graduallyreleased and can be directly taken up by the stomata of the plants.Losses in CO₂ are extremely slight, because the release of the carbondioxide gas from the nutrient solution takes place directly adjacent tothe stomata and is further accomplished in quantities dosed in responseto the degree of water evaporation, with the gas concentrationincreasing above the limit of the natural bond. Hence, the irrigationwater drips act as CO₂ dispensers available on call. The plants are thusenabled to directly take up and utilize up to 90% or more of thenutrients.

It will be advantageous if the CO₂ content of the solution and water,respectively, is selected such that an increased solubility of the waterfor nutrient salts results in a way as to exclude any depositing of thedissolved substances throughout the entire supply system as well.

It will be expedient if the CO₂ content is adjusted between 0.5 and 2g/l water. Advantageously, the content may be reduced up to 0.1 g/l.

The water qualities differing nowadays with regard to carbon dioxide,are to be taken into account in this connection. Irrigation or dressingwater is generally gained from rain or tap water or from a mixturethereof, partly also from surface or ground water, gained from rain aswell.

Nowadays, rain has a relatively low carbon dioxide content though theconcentration in the atmosphere has seriously increased in the course ofthe last century. This is due to the fact, that the absorptive power ofa condensate is generally higher with regard to sulphur dioxide--atequal atmospheric bonds and at a temperature of about 20°C.--absorptivity amounts to about 40 l SO₂ per liter water compared to0.88 l CO₂. CO₂ is also liberated from the tap water for technologicalreasons (protection against corrosion), which means, the content isextremely reduced (viz. German magazine "Bild der Wissenschaft", No.11/84 "on the formation of mineral water", especially, page 52). Thisarticle simultaneously emphasizes the high solvency of the carbonic acidto which the same importance is attached in botany for the availabilityto the root. Practical experiments have shown that one of the mainreasons for the plant infestation today is to be seen in a CO₂ -- and H₂CO₃ deficiency. Carbonic acid has a germ-inhibitory effect. The qualityof mineral water, for example, is thus naturally preserved.

The reflections on plants in this connection are also applicable to thetake-up of minerals and the like for animals and human beings.

The following, essential advantages of the new method are to beemphasized:

Owing to the increased CO₂ content, the solubility of the water for thenutrient salts and consequently, the nutrient uptake directly throughthe leaves of the plants is substantially improved.

Simultaneously with the impregnated nutrient solution, the leaves andthe plants are supplied, via the stomata, with CO₂ required by theplants for assimilation. The fact is, that CO₂ is supplied in dosedquantities and thus, the method can be deemed extremely economical. Itis the particularly distinctive characteristic of CO₂ --the capabilityof passing through the cell membranes with less difficulty than most ofthe other substances--that is utilized in this connection. Moreover, CO₂reaches all tissue substances.

When a nutrient solution impregnated with CO₂ is employed, the use offungicides or other pesticides may be substantially reduced, since CO₂has a germ inhibitory effect and also heightens the resistance of theplants. Savings of about 50% or more may be attained.

Deposits and incrustations in the conduits and spraying system areexcluded due to the increased CO₂ content in the nutrient solution, thesame applies to pore clogging and spotting due to deposits on the leafsurface.

Compared to the conventional atmosphere dressing by introducing CO₂ gasinto the greenhouse atmosphere, the losses in CO₂ are extraordinarilyslight so that the method can be accomplished in a particular economicalmanner.

In the nutrient solution settled on the leaves, CO₂ is buffered and onlygradually made available to the stomata of the plants in the course ofthe evaporation of the liquid.

Upon large scale employment of the method, the costs may be furthersubstantially reduced by fine impregnating the water with CO₂ gainedfrom the recovery of exhaust gases, in particular, flue gases, forexample, from power plants, and having only a technical purity, whichmeans, a percentage purity of about or less than 99.5%. The method canthus be also employed in the open field in agriculture.

Due to the fact that technically pure CO₂ gained from flue gases isused, the CO₂ concentration in the troposphere, which negativelyinfluences the climate, is reduced at the same time. Pesticides can belargely dispensed with when the new method is employed or, at least, thequantities used can be substantially reduced.

Furthermore, economy is increased by the new technology owing to thefact that it will be possible to more selectively adjust the fertilizerto the actual needs of the plants and consequently, fertilizers can bealso saved.

It is further known, that the high quantities of fertilizers nowadaysemployed in agriculture cause increasing loads to the ground water. Onthe one hand, this is substantially due to the fact that the plants arenot capable of completely utilizing the nutrients artificiallyintroduced into the soil and, on the other hand, that the soil itselfcannot maintain the high nutrient concentrations. Hence, the nutrients,in particular, nitrogen compounds, are flushed into the ground water inan uncontrolled manner. The new method of leaf dressing disclosedhereinbefore, serves to largely exclude this danger.

In many cases it will not suffice to supply nourishment only by means ofleaf dressing. Even better and more favorable conditions for both theplants and ground water will be achieved upon combining the leafdressing and the fertilization of the soil. Advantageously a combineddressing method of the "splitting type" is employed according to whichthe aqueous solution impregnated with CO₂ and intended to be applied inleaf dressing is substantially enriched with nutrients, herbicides orpesticides loading the ground water, such as nitrogen compounds, traceelements or the like, whereas the remaining nutrients, herbicides orpesticides are either directly or in the form of a nutrient solutionintroduced into the arable land.

Experiments have shown, that only specific nutrient salts are subject tothe danger of being flushed into the ground water. Above all, nitrogencompounds and trace elements are counted among these specific elements.

If the nutrient elements particularly loading the ground water areselectively applied by means of the improved leaf dressing methodaccording to the invention the ground water will remain largely freefrom these loading substances, since--as depicted hereinbefore--theimproved method takes care of a selective and almost complete uptake ofthe nutrient salts applied by leaf dressing.

The nutrient salts hardly or only slightly loading the ground water canbe either directly or separately from the ground water loadingsubstances introduced into the soil in the case of the new method, whichmeans, the substances can be introduced by means of one of theconventional methods, advantageously, however, in the form of a nutrientsolution impregnated with CO₂, as well. Dressing is thus accomplished bya sort of splitting method, with it being also possible to apply ordischarge the nutrient salts directly introduced into the soil in theconventional dry, granular form.

The new splitting method essentially reduces the loads to both the soiland ground water caused by excessive nutrient substances and salts,allows a more selective fertilization and results in essential savingsin salt quantities.

The disadvantages of the progressive humus depletion of the soil and itsconsequences can be compensated in an economical and ecologicallyreasonable manner by the new method.

In addition, the use of herbicides, fungicides and other insecticidescan be drastically reduced with the new method, for example, up to 50%or more, and consequently, the soil and ground water load caused by thesubstances is reduced to a large extent, as well. It is to be observedthat a lot of these substances are hardly degradable or degradation israther difficult. Besides the quantitative improvement of the nutrientuptake, there is also a qualitative improvement (formation ofhydrogencarbonates). The increased absorbing capacity of the plantsurface for nutrients is maintained over a relatively long period oftime in the case of the new method, since the CO₂ concentration in thediminishing water volume is maintained when the water evaporates untilthe absorption through the surface has terminated. The supply of CO₂ andthus of the nutrients is accomplished in dosed quantities.

The increased solubilizing concentration for nutrients caused by theimpregnation with CO₂ results in an increase in the osmotic pressure onthe plant surface. Therefore, the nutrients are capable of better andfaster penetrating into the leaf. Owing to the presence of CO₂, thepermeability is improved as well. Either of the two factors is decisivefor an improvement of the surface absorption, with the solutions alsoreaching the organellae.

We claim:
 1. A method of increasing solubility of plant nutrient saltsin a solution for promoting plant growth via foliar application of saidsolution, comprising the steps of:preparing an aqueous solution of atleast one plant-nutrient salt; impregnating said aqueous solution withcarbon dioxide to a carbon dioxide concentration in the water of 0.10 to2 grams per liter and wherein said concentration is in a range of thenormal absorption capacity of the water for the carbon dioxide atambient temperature and pressure; and dispersing the resulting carbondioxide impregnated aqueous solution of said plant-nutrient saltprimarily on leaves of plants growing at said plant growth site.
 2. Themethod defined in claim 1 wherein said water is initially impregnatedwith said carbon dioxide to said concentration and at least one compoundselected from the group which consists of said nutrient salt, anherbicide and a pesticide is thereafter dissolved in the carbon dioxideimpregnated water.
 3. The method defined in claim 1 wherein said carbondioxide is a technical grade carbon dioxide with a CO₂ content of lessthan 99.5% and obtained by carbon dioxide recovery of an industrialplant exhaust gas.
 4. The method defined in claim 1 wherein saidsolution is impregnated with said carbon dioxide after said nutrientsalt has been dissolved therein and at least one compound selected fromthe group which consists of an herbicide and a pesticide is thereafteradded to said solution at least by the time said solution is dispersedonto the leaves of said plants.